Posted at the Institutional Resources for Unique Collection and Academic Archives at Tokyo Dental College, Available from http://ir.tdc.ac.jp/
Author(s) Kanemoto, T; Imai, H; Sakurai, A; Dong, H; Shi, S;
Yakushiji, M; Shintani, S
Journal Bulletin of Tokyo Dental College, 57(3): 143‑157 URL http://hdl.handle.net/10130/5792
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Description
Influence of Lifestyle Factors on Risk of Dental Caries among Children Living in Urban China
Taeko Kanemoto1), Hiroki Imai1), Atsuo Sakurai1), Hongwei Dong2), Sizhen Shi2), Masashi Yakushiji1) and Seikou Shintani1)
1) Department of Pediatric Dentistry, Tokyo Dental College, 2-9-18 Misaki-cho, Chiyoda-ku, Tokyo 101-0061, Japan
2) Research Institute of Pediatric Dentistry, Tongji University,
2, Lane 158, DaMuQiao Rd., Ste. 402 Shanghai, 200032, PR China Received 14 January, 2016/Accepted for publication 23 February, 2016
Abstract
The prevalence of dental caries has been decreasing among kindergarten children in Shanghai, China, over recent years, although it still remains at an unacceptably high level. The purpose of this study was to identify which factors were important in providing oral health guidance and achieving further improvement in the oral health status of kindergarten children in urban China. A survey was conducted on dental caries in 128 Japanese and 368 Chinese kindergarten children and a questionnaire given to their par- ents/guardians on each child’s lifestyle and dietary habits from birth to the present.
Correlations between responses to each questionnaire item and the status of dental caries were statistically analyzed. The dft index score (p=0.0016), prevalence of dental caries (p=0.0002), and percentages of children with decayed (untreated caries-affected) teeth (p<0.0001) were significantly higher in the Chinese than in the Japanese children. Many differences were observed in lifestyle factors between the two groups. The percentage of parents failing to control the child’s snacking habits between meals was higher in China, and weaning was significantly delayed in China compared with in Japan. These lifestyle factors were considered to be associated closely with the high risk of dental caries in Chinese kindergarten children. These findings indicate that oral health guidance for kindergarten children in Shanghai, China, should focus on control of dietary habits, including control of inter-meal snacking, and breastfeeding practices. The results of this study may help improve the status of dental caries among Chinese children.
Key words: Deciduous tooth caries — Oral health — Questionnaire — Chinese children — Shanghai
This paper was a thesis submitted by Taeko Kanemoto to the Graduate School of Tokyo Dental College.
143
In the People’s Republic of China (herein- after simply called “China”), remarkable eco- nomic growth has been accompanied by major change in dietary habits2,5,25,29). Such change, however, has been predicted to have a negative impact on oral health in children, with a concomitant elevation in risk of caries.
Against this background, in 1988, the Chinese Government commissioned a committee of experts to look at ways of improving preven- tive dentistry and promoting oral health. The effects of these measures, however, remain virtually unknown11,23).
Since 1994, this group has been periodi- cally investigating the status of dental caries and oral health guidance for kindergarten children and their guardians in Shanghai11). Although some similar studies have noted a decrease in the prevalence of dental caries among kindergarten children, the results have still been poor in comparison with those observed in Japan during the same period11,17).
Shanghai is a coastal city. Economically powerful, it sees large inflows and outflows of people and is home to a population of wide ethnic diversity. An understanding of the importance of maintaining and improving oral health from childhood onward would improve the quality of life for many of its citi- zens. Moreover, this would serve as a model for disseminating such knowledge through- out the rest of the country. However, the pro- motion of oral health guidance in Japan is tailored to the lifestyle there, and there is no guarantee that the same approach would work in China too. Therefore, before such methods can be adopted for the Chinese population, it is necessary to determine how lifestyle factors will affect how this should be done.
The purpose of this study was to identify which factors were responsible for the high risk of dental caries observed in Chinese chil- dren. A survey was conducted on dental caries among kindergarten children in Shanghai and a questionnaire given on their diets and lifestyles. The results were then compared
Materials and Methods 1. Participants
The participants comprised 128 children attending a kindergarten in Funabashi City, Chiba Prefecture, Japan and 368 children attending 2 kindergartens in Shanghai, China (Table 1). All the children were aged between 3 and 6 years. Kindergarten education lasts for 3 years in China, beginning at the age of 3, identical to the kindergarten system adopted in Japan. The socioeconomic status of the Chinese children and their families was deemed to be relatively high compared with the national average. Therefore, a Japanese kindergarten in the city of Funabashi, close to the Tokyo metropolitan area, was chosen as a suitable control group. Oral health guidance has been provided for approximately 20 years in all the kindergartens surveyed, but no fluo- ride was used for prevention of dental caries.
A survey on dental caries and a questionnaire for parents/guardians were implemented in both groups, in November 2012 for the Chi- nese children and in June 2013 for the Japa- nese children. The school year begins in September in China, whereas it begins in April in Japan. The study protocol was approved by the Tokyo Dental College Ethics Committee (Approval No. 286).
2. Survey of dental caries
In China, the status of dental caries was surveyed by a single Chinese dentist in the presence of a Japanese dentist. In Japan, the same examination was carried out by another single Japanese dentist, a specialist in pediat- ric dentistry. The examination given was the same as that used for dental health checkups in schools throughout Japan, employing a health checkup illumination system and den- tal mirror. In China, both dentists checked the oral cavities of several children in advance, and adjustments were made on the basis of the results of this preliminary checkup to
avoid discrepancies between the two coun- tries in the method employed for the main examination. The diagnosis of dental caries was based on the WHO criteria, with records taken of the status of caries of the deciduous
teeth and the dft index28). 3. Questionnaire
A questionnaire, in Japanese or Chinese as appropriate (Table 2), was given to the par-
Table 1 Kindergarten children surveyed in Japan and China
Japan China
All children Boys Girls All children Boys Girls
Minor (aged 3 or 4 yr) 35 18 17 119 76 43
Middle (aged 4 or 5 yr) 47 22 25 139 90 49
Elder (aged 5 or 6 yr) 46 17 29 110 67 43
Total 128 57 71 368 233 135
【版面】W：396 pt（片段 192 pt） H：588 pt 【本文】行数不明（インデザイン手組み） 10pt 12pt 送り
【図】●図番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std 図タイトルと説明のアキ 9Q ●タイトル折り返し：番号の後（続 く説明の先頭は字下げ不要） ●図説の幅 片段：片段固定 全段：図幅
【表】●番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std タイトルと表のアキ 10.5Q ●罫線 表はじめのみ双罫 表中の 罫の太さ 1.411mm ●表中：11.3Q 12.7H New Baskerville ITC Std ●脚注 11.3Q 12.7H New Baskerville ITC Std 字下げなし 斜体は New Baskerville ITC Std Italic（タグは <l>）ギリシア文字は Greek with Math Pi（文字スタイル設定済み）
Table 2 Items contained in questionnaire on lifestyle and dietary habits of children 1. When does the child brush their teeth?
2. How often does the child brush his/her teeth every day?
3. How often does the parent/guardian perform final brushing?
4. Is toothpaste used?
4-1. If toothpaste is used, does the paste contain fluoride?
5. Has the child received guidance on tooth brushing?
6. How often does the child ingest snacks per day?
7. When does the child ingest snacks?
8. Who selects the foods taken as snacks?
9. When did the child begin taking snacks?
10. Does the child eat 3 meals at regular times of the day?
11. Does the child eat his/her meals with other family members?
12. Do you feel that the child eats too fast or too slowly?
13. Do you feel the child eats large amounts or small amounts of food?
14. Do any of the following hold true for your child during meals?
Watches TV Is picky about food
Ingests food with water or tea without sufficient chewing Keeps the food in the mouth for a long time
Talks excessively Dislikes hard foods
Makes loud sounds while eating
Does not eat sufficiently because of untimely ingestion of snacks 15. How often does the family eat outdoors?
16. Did the child receive breastfeeding only, bottle-feeding only, or both?
17. Did the child receive milk feeds at bedtime?
17-1. If yes, until what age did the child receive feeds at bedtime?
18. At what age was weaning achieved?
19. Did the child receive dental care?
19-1. If yes, why did the child visit the dental clinic?
20. Have you ever looked up any information on oral health?
21. Do you know about the effects of fluoride in preventing dental caries?
21-1. If yes, are you using fluorides for preventing dental caries?
22. Who are the members constituting your family?
23. When does the child get up in the morning and when does he/she go to bed at night?
24. Has the child developed any illness requiring hospitalization?
24-1. If yes, what was the diagnosis?
25. Does the child suffer from allergy to any food or drug?
ents/guardians on each child’s dietary habits and lifestyle from birth to the present. It con- sisted of items on factors reported to be asso- ciated with the onset of dental caries in the literature7,12,18,20). In addition, the parent/
guardian was asked to list all the foods/drinks ingested, the time of ingestion, tooth brush- ing habits and whether final brushing was conducted by the adult each day over a 4-day period.
4. Statistical analysis
The results for each country were com- pared and correlations between lifestyle fac- tors or dietary habits with the risk of dental caries in the Chinese children statistically analyzed. Responses to individual items served as independent variables and experi- ence of dental caries and presence/absence of decayed teeth as dependent variables. The statistical analysis was performed using the JMP® software (version 10.0.2; SAS Institute Inc., NC, USA). The Student’s t-test was used to compare the number of teeth with caries.
The chi-square test was used to compare life- styles, prevalence of dental caries, and per- centages of children with decayed teeth between Japan and China. If any cells in the contingency table were less than 5, the Fish- er’s exact test was applied instead of the chi- square test. A p value of <0.05 was regarded as statistically significant. To predict risk of dental caries in Chinese children, a multiple logistic regression analysis using the stepwise
method was employed and the odds ratios for factors possibly involved in the development of dental caries calculated. The model thus created was evaluated by the goodness-of-fit test. A p value of <0.05 by the goodness-of-fit test implied that the model was adequate.
Results
1. Status of dental caries in Japan and China Table 3 shows the dft score, prevalence of dental caries, and percentages of children with decayed teeth in Japan and China. The number of caries-affected teeth, dft score, prevalence of dental caries, and percentages of children with decayed teeth were signifi- cantly higher in Chinese than in Japanese children. On the other hand, the number of treated teeth was significantly higher in Japa- nese children. In both Japan and China, the dft score, prevalence of dental caries, and percentage of children with decayed teeth tended to be higher in girls than in boys, although the difference was not statistically significant. When analyzed by the school year, children from both the minor and middle grades in China had a significantly higher dft score, prevalence of dental caries, and per- centages of decayed teeth than children in Japan (Table 4).
Table 3 Comparisons of status of dental caries in kindergarten children between Japan and China
Japan China
p value All children Boys Girls All children Boys Girls
Decayed teeth 0.52 0.44 0.59 1.99 1.92 2.11 <0.0001
Filled teeth 0.69 0.72 0.66 0.27 0.30 0.22 0.0038
dft index 1.21 1.16 1.25 2.26 2.22 2.33 0.0016
Prevalence of dental caries (%) 28.9 26.32 30.99 47.8 45.49 51.85 0.0002 Persons with decayed teeth (%) 14.8 14.04 15.49 46.5 44.41 50.37 <0.0001 p values refer to comparison of subjects between Japan and China. Tested with Student’s t-test and chi-square test.
No significant difference was observed between boys and girls in both Japan and China.
2. Differences in lifestyle factors between Japan and China based on questionnaire Responses to the questionnaire were col- lected from 104 participants in Japan (response rate: 81.3%) and 172 in China (46.7%). A comparison of the responses to the questions (including the information col- lected from the meal record form) between Japan and China is shown in Table 5.
The questionnaire revealed many differ- ences in lifestyle between Japan and China.
The following were characteristics of the life- style in China: i) tooth brushing was often performed before breakfast, but few children brushed their teeth after each of their 3 meals;
ii) the parent/guardian only performed final brushing infrequently; iii) few parents/guard- ians provided fluoride in toothpaste or in any other form; iv) many children ingested snacks three times or more daily, although there were some children who did not have the habit of snacking at all; v) a high frequency of snack ingestion after supper; vi) snacks were selected not only by the mother, but also sometimes by the father; vii) regular meals were taken, but without the attendance of any family members in many cases; viii) eating outdoors was frequent; ix) the breastfeeding period was prolonged, with breastfeeding at night continued for particularly long periods of time.
3. Correlation between responses to questionnaire and prevalence of caries in deciduous teeth
The prevalence of dental caries and per- centages of children with decayed teeth among Chinese children were calculated after they had been grouped according to responses to the questionnaire. The data col- lected were analyzed with the chi-square test to identify which lifestyle factors influenced the prevalence of dental caries or percentages of children with decayed teeth (Table 6). The following factors were found to be associated with an increase in the prevalence of dental caries and/or the percentages of children with decayed teeth: i) failure of the parent/
guardian to perform final tooth brushing every day; ii) ingestion of snacks once or more frequently per day; iii) ingestion of snacks before breakfast; iv) ingestion of snacks between supper and bedtime; v) snacks selected by the children themselves; vi) absence of regular intake of three meals; vii) insufficient amount of food at mealtimes; viii) watching TV during intake of meals; ix) picki- ness about food; x) talking excessively during intake of meals; and xi) weaning at the age of 25 months or later. Unexpectedly, the risk for dental caries was found to be lower in the group not using toothpaste for tooth brush- ing (xii). When the children were grouped according to timing of ingestion of snacks,
Table 4 Status of dental caries among children in each year of kindergarten
Minor Middle Elder
Japan China p value Japan China p value Japan China p value
Decayed teeth 0.23 1.53 0.0098 0.55 2.37 0.0003 0.72 2.01 0.0090
Filled teeth 0 0.22 N.S. 0.96 0.32 0.0174 0.93 0.26 0.0036
dft index 0.23 1.75 0.0102 1.51 2.70 0.0378 1.65 2.27 N.S.
Prevalence of
dental caries (%) 8.57 38.66 0.0003 34.04 53.96 0.0174 39.1 50.0 N.S.
Persons with
decayed teeth (%) 8.57 36.97 0.0005 17.02 53.24 <0.0001 17.4 48.2 0.0002 p values refer to comparisons of children in same year of kindergarten between Japan and China. Tested with Student’s t-test and chi-square test. N.S.: Not significant.
Table 5 Comparison of responses to questionnaire between Japan and China Number answering “Yes”/subjects
p value
Japan (%) China (%)
Timing of brushing teeth (multiple answers permitted)
Before breakfast 2/104 1.9 118/167 70.7 <0.0001
After breakfast 75/104 72.1 21/167 12.6 <0.0001
After lunch 74/104 71.2 0/167 0 <0.0001
After supper 34/104 32.7 6/167 3.6 <0.0001
At bedtime 69/104 66.4 125/167 74.9 N.S.
No brushing 0/104 0 3/167 1.8 N.S.
Frequency of brushing teeth
Once daily or more 71/72 98.6 137/143 95.8 N.S.
Twice daily or more 52/72 72.2 72/143 50.4 0.0019
Thrice daily or more 16/72 22.2 1/143 0.7 <0.0001
Final brushing
Done every day 79/103 76.7 41/159 25.8 <0.0001
Done every day or occasionally 102/103 99.0 107/159 67.3 <0.0001 Use of toothpaste
Present 89/104 85.6 134/144 93.1 N.S.
Fluoride-containing toothpaste
Selected product used 75/104 72.1 48/144 33.3 <0.0001
History of receiving guidance on brushing method
Present 98/103 95.2 102/160 63.8 <0.0001
Frequency of snack ingestion
Once daily or more 102/104 98.1 117/158 74.1 <0.0001
Twice daily or more 23/104 22.1 47/158 29.8 N.S.
Thrice daily or more 6/104 5.8 16/158 10.1 N.S.
Time of snack ingestion (multiple answers permitted)
Before breakfast 2/102 2.0 3/147 2.0 N.S.
Between breakfast and lunch 20/102 19.6 26/147 17.7 N.S.
Between lunch and supper 102/102 100.0 98/147 66.7 <0.0001
Between supper and bedtime 4/102 3.9 46/147 31.3 <0.0001
Times other than interval
between lunch and supper 23/102 22.6 76/147 51.7 <0.0001
Who selects the snacks for the child (multiple answers permitted)
Child himself/herself 60/104 57.7 98/166 59.0 N.S.
Mother 92/104 88.5 76/166 45.8 <0.0001
Father 4/104 3.9 35/166 21.1 <0.0001
Grandparent 21/104 20.2 41/166 24.7 N.S.
Age at start of snack ingestion
Before 1 year of age 7/66 10.6 10/106 9.4 N.S.
Before age of 2 years 52/66 78.8 49/106 46.2 <0.0001
Before age of 3 years 65/66 98.5 77/106 72.6 <0.0001
Number answering “Yes”/subjects
p value
Japan (%) China (%)
Dietary style
Taking 3 meals regularly 91/103 88.4 162/170 95.3 0.0362
Breakfast & supper taken with all family members 80/103 77.7 104/170 61.2 0.0042
Breakfast & supper taken alone 0/103 0 15/170 8.8 0.0001
Eating rapidly 8/104 7.7 58/170 34.1 <0.0001
Eating slowly 39/104 37.5 12/170 7.1 <0.0001
Eating large amounts 4/104 3.9 15/156 9.6 N.S.
Eating small amounts 30/104 28.9 29/156 18.6 N.S.
Scenes while eating (multiple answers permitted)
Watches TV 55/104 52.9 67/157 42.7 N.S.
Picky about food 43/104 41.4 48/157 30.6 N.S.
Eats without chewing sufficiently 1/104 1.0 48/157 30.6 <0.0001
Keeps food pooled in mouth 11/104 10.6 29/157 18.5 N.S.
Talks excessively 43/104 41.4 77/157 49.0 N.S.
Dislikes hard foods 1/104 1.0 37/157 23.6 <0.0001
Makes loud sounds while eating 6/104 5.8 8/157 5.1 N.S.
Does not each much because of
frequent/untimely snacking 6/104 5.8 9/157 5.7 N.S.
Frequency of eating outdoors
Once a week or more 21/103 20.4 58/144 40.3 0.0008
Twice a week or more 3/103 2.9 18/144 12.5 0.0046
Three times a week or more 0/103 0 6/144 4.2 0.0103
Milk feeding
Breastfeeding only 34/103 33.0 30/160 18.8 0.0091
Bottle-feeding only 23/103 22.3 32/160 20.0 N.S.
Weaning at 13 months or more 75/99 75.8 57/84 67.9 N.S.
Weaning at 19 months or more 36/99 36.4 51/84 60.7 0.0010
Weaning at 25 months or more 13/99 13.1 38/84 45.2 <0.0001
Feeding at night continued until 13 months or more 31/63 49.2 84/104 80.8 <0.0001 Feeding at night continued until 19 months or more 14/63 22.2 75/104 72.1 <0.0001 History of receiving dental care
Present 70/103 68.0 55/160 34.4 <0.0001
Oral health
History of searching for information on oral health 33/100 33.0 14/69 20.3 N.S.
History of use of fluorides other than in toothpaste
Having used 32/99 32.3 3/50 6.0 <0.0001
Family composition (multiple answers permitted)
Living with both parents 100/104 96.2 143/158 90.5 N.S.
Living with grandparent(s) 33/104 31.7 110/158 69.6 <0.0001
Having sibling/s 83/104 79.8 18/158 11.4 <0.0001
Table 5, continued
significant differences were found in the prevalence of dental caries and percentages of children with decayed teeth, depending on multiple categories related to timing of snack ingestion. In the logistic regression analysis described below, a new variable, “snack inges- tion at times other than the interval between lunch and supper (xiii)” was entered, but
“ingestion of snacks before breakfast (iii)”
and “ingestion of snacks between supper and bedtime (iv)” were omitted. Thus, 11 factors were used as independent variables in further analysis. The children were grouped again according to the status of this additional cat- egory and prevalence of dental caries and percentages of children with decayed teeth recalculated (Table 5, 6).
The multiple logistic regression analysis was conducted to identify which factors pos- sibly exerted a marked impact on the risk of dental caries among Chinese children. The analysis revealed that the risk of dental caries was higher when the children selected their own snacks, when snacking occurred at some time other than between lunch and supper, when they talked excessively during meals, and/or when they were weaned only at the age of ≥25 months (Table 7). Furthermore, the timing of snack ingestion and prolonged breastfeeding were also revealed as lifestyle factors showing a significant difference between Japan and China.
Discussion
Periodic surveys of children in kindergar- ten in Shanghai by this group have revealed a decrease in the prevalence of dental caries.
However, in the present study, all the scores for caries-affected teeth, prevalence of dental caries, percentages of children with decayed teeth, and the dft index were significantly higher in the Chinese than in the Japanese children, suggesting the need for further effort towards improvement (Table 3). Fur- thermore, the mean number of decayed teeth was also significantly higher among children in China. These results are similar to those of earlier studies on dental caries by this group in 1994 and 2004 and those of other groups
also11,30). This indicates the need for more edu-
cation on the importance of treating caries in deciduous teeth in China. The mean number of treated teeth per child was significantly higher in Japanese children. It is not clear whether this was due to the greater propor- tion of dentists to the total population in Japan or differences in the level of awareness of oral health, however. The response rate to the questionnaire and adherence to keeping a record of meals was lower in China, even though the socioeconomic status of the fami- lies involved was relatively high, indicating that work still needs to be done on raising awareness of oral health.
Number answering “Yes”/subjects
p value
Japan (%) China (%)
Duration of sleep
10 hours or more 69/99 69.7 45/86 52.3 0.0152
History of hospitalization
Present 16/104 15.4 12/73 16.4 N.S.
History of food/drug allergy
Present 13/104 12.5 14/72 19.4 N.S.
p values refers to comparisons between Japan and China. Tested with chi-square test or Fisher’s exact test. N.S.:
Not significant.
Table 5, continued
Table 6 Status of caries of the deciduous teeth in Chinese children as analyzed from the responses to the ques- tionnaire
Response to questionnaire Prevalence of dental caries (%) Persons with decayed teeth (%)
Yes No p value Yes No p value
Timing of brushing teeth (multiple answers permitted)
Before breakfast 40.5 50.9 N.S. 39.7 47.3 N.S.
After breakfast 47.2 43.0 N.S. 42.9 41.8 N.S.
After lunch — 43.6 N.D. — 41.9 N.D.
After supper 57.1 43.0 N.S. 57.1 41.3 N.S.
At bedtime 43.0 39.2 N.S. 41.4 39.6 N.S.
No brushing 75.0 42.9 N.S. 75.0 41.2 N.S.
Frequency of brushing teeth
Once daily or more 41.6 66.7 N.S. 40.9 50.0 N.S.
Twice daily or more 41.7 43.7 N.S. 41.7 40.9 N.S.
Thrice daily or more 0 43.0 N.S. 0.0 41.6 N.S.
Final brushing
Done every day 31.6 77.8 0.0097 31.6 49.6 0.0225
Done every day or occasionally 41.3 55.8 N.S. 39.7 53.9 N.S.
Use of toothpaste
Present 44.4 19.1 0.0211 42.4 19.1 0.0328
Fluoride-containing toothpaste
Selected product used 56.3 41.7 N.S. 54.2 39.6 N.S.
History of receiving guidance on brushing method
Present 42.2 43.1 N.S. 41.3 41.7 N.S.
Frequency of snack ingestion
Once daily or more 49.2 31.8 0.0419 48.5 27.3 0.0123
Twice daily or more 49.1 43.0 N.S. 49.1 40.5 N.S.
Thrice daily or more 61.1 43.0 N.S. 61.1 41.1 N.S.
Time of snack ingestion (multiple answers permitted)
Before breakfast 100.0 45.1 0.0299 100.0 43.2 0.0259
Between breakfast and lunch 55.2 44.1 N.S. 55.2 41.9 N.S.
Between lunch and supper 39.1 60.0 0.0110 39.1 54.6 N.S.
Between supper and bedtime 59.6 39.8 0.0177 57.7 38.1 0.0184
Times other than interval between lunch
and supper 55.8 35.4 0.0085 53.5 34.2 0.0122
Who selects snacks for child (multiple answers permitted)
Child himself/herself 48.6 36.6 N.S. 48.6 32.9 0.0305
Mother 44.4 42.3 N.S. 41.1 42.3 N.S.
Father 41.5 42.8 N.S. 41.5 41.8 N.S.
Grandparent 34.6 46.7 N.S. 34.6 44.4 N.S.
Response to questionnaire Prevalence of dental caries (%) Persons with decayed teeth (%)
Yes No p value Yes No p value
Age at start of snack ingestion
Before 1 year 30.0 43.8 N.S. 30.0 41.7 N.S.
Before 2 years 44.9 40.4 N.S. 42.9 38.6 N.S.
Before 3 years 44.2 37.9 N.S. 42.9 34.5 N.S.
Dietary habits
Taking 3 meals regularly 41.5 100.0 0.0002 39.0 100.0 0.0002
Breakfast & supper taken with all family
members 44.7 41.7 N.S. 43.9 39.0 N.S.
Breakfast & supper taken alone 27.8 45.1 N.S. 27.8 43.4 N.S.
Eating rapidly 37.9 47.2 N.S. 37.9 44.8 N.S.
Eating slowly 58.3 43.0 N.S. 58.3 41.3 N.S.
Eating large amounts 26.3 46.5 N.S. 26.3 44.6 N.S.
Eating small amounts 69.0 39.5 0.0034 69.0 37.4 0.0017
Scenes while eating (multiple answers permitted)
Watches TV 53.3 38.2 0.0458 52.0 36.3 0.0367
Picky about food 58.0 39.4 0.0250 58.0 37.0 0.0113
Eats without chewing sufficiently 40.4 46.4 N.S. 40.4 44.0 N.S.
Keeps food pooled in mouth 58.1 41.8 N.S. 58.1 39.7 N.S.
Talks excessively 52.9 37.0 0.0323 50.6 35.9 0.0478
Dislikes hard foods 51.2 42.7 N.S. 51.2 40.4 N.S.
Makes loud sounds while eating 44.4 44.4 N.S. 44.4 42.6 N.S.
Does not each much because of frequent/
untimely snacking 55.6 44.1 N.S. 55.6 42.3 N.S.
Frequency of eating outdoors
Once a week or more 36.9 47.9 N.S. 35.4 45.8 N.S.
Twice a week or more 45.0 43.3 N.S. 45.0 41.1 N.S.
Three times a week or more 66.7 42.6 N.S. 66.7 40.7 N.S.
Milk feeding
Breastfeeding only 45.7 43.8 N.S. 45.7 41.8 N.S.
Bottle-feeding only 41.7 44.8 N.S. 38.9 43.5 N.S.
Weaning at 13 months or more 57.9 39.4 N.S. 56.1 36.4 N.S.
Weaning at 19 months or more 56.9 43.6 N.S. 54.9 41.0 N.S.
Weaning at 25 months or more 63.2 42.3 0.0496 60.5 40.4 N.S.
Feeding at night continued until 13 months
or more 45.6 40.0 N.S. 44.4 40.0 N.S.
Feeding at night continued until 19 months
or more 43.8 46.7 N.S. 42.5 46.7 N.S.
History of receiving dental care
Present 65.5 34.1 <0.0001 60.0 34.1 0.0012
Table 6,continued
The purpose of the present study was to identify which factors were important in pro- viding oral health guidance and improving dental health among Chinese children.
Towards this end, two methods were employed. First, a questionnaire was designed to compare lifestyle factors between Japan and China (Table 5). If any of the precautions urged in Japan in relation to lifestyle elements were not sufficiently practiced in China, they were to be considered as candidate topics of focus in improving oral health guidance.
However, since the cultures differ between Japan and China, it may be difficult to apply the type of oral health guidance provided in Japan, which is tailored to the Japanese life- style, directly to the Chinese population5,12). Second, the Chinese children were grouped according to responses to the questionnaire, and prevalence of dental caries and percent-
ages of children with decayed teeth in each group calculated. Our goal was to identify which lifestyle factors were associated with an increase in the risk of dental caries among Chinese children by comparing data between these groups (Table 6). It was anticipated that each factor identified by both the first and second methods would deserve attention as a point of importance in providing oral health guidance.
Chinese children often brushed their teeth before breakfast, but only infrequently after each meal, possibly because many people are in the habit of eating outdoors in China, even breakfast16). Awareness that brushing immedi- ately after each meal is the most effective way of maintain oral health appears to be low, sug- gesting that education on the importance of brushing soon after lunch in kindergarten should be part of any guidance given on oral
Response to questionnaire Prevalence of dental caries (%) Persons with decayed teeth (%)
Yes No p value Yes No p value
Oral health
History of searching for information on oral
health 57.1 50.9 N.S. 53.3 47.0 N.S.
History of use of fluorides other than in toothpaste
Having used 100.0 50.0 N.S. 66.7 44.4 N.S.
Family composition (multiple answers permitted)
Living with both parents 41.7 60.0 N.S. 39.9 60.0 N.S.
Living with grandparent(s) 41.9 46.3 N.S. 40.3 44.4 N.S.
Having sibling/s 50.0 42.4 N.S. 45.0 41.1 N.S.
Duration of sleep
10 hours or more 44.4 48.8 N.S. 48.8 42.2 N.S.
History of hospitalization
Present 50.0 52.5 N.S. 50.0 50.8 N.S.
History of food/drug allergy
Present 42.9 53.5 N.S. 42.9 51.7 N.S.
Prevalence of dental caries and percentages of children with decayed teeth among Chinese children at time of check up were calculated from responses (Yes/No).
p values refer to comparison among groups with different responses. Tested with chi-square test or Fisher’s exact test.
N.D.: Not determined because of absence of corresponding Chinese child. N.S.: Not significant.
Table 6,continued
health. The percentage of parents/guardians performing final brushing every day was sig- nificantly lower in China, and the prevalence of dental caries and percentages of children with decayed teeth were high in the Chinese.
Moreover, these figures were also higher in the group in which final brushing was only occasionally performed by the parent/guard- ian in comparison with in the group in which it was performed every day (data not shown), indicating that the effect of tooth brushing in preventing dental caries was low unless final brushing was practiced on a daily basis20,27).
The prevalence of dental caries was found to be significantly higher among children using toothpaste. Toothpaste often contains fluoride, which should prevent dental caries.
This suggests that the contents of toothpaste products sold in China should be investigated.
However, the percentage of responders answering that they did not know whether they were using fluoride-containing tooth- paste was significantly higher in China than in Japan (data not shown). Moreover, the response rate was particularly low to questions on experience of fluoride utilization through products other than toothpaste. This result was consistent with those of earlier studies suggesting that knowledge of the effects of fluoride in preventing dental caries is not yet widespread in China21,32). In the present study,
fluoride use was not identified as a point of focus for providing oral health guidance, maybe due to the low response rate. If knowl- edge of the usefulness of fluoride in prevent- ing caries were disseminated more widely, it might gain in importance8,13,19,23). In addition, utilization of toothpaste by children might shorten brushing time. Therefore, a more detailed investigation is needed on the status of tooth brushing by children in China.
The prevalence of dental caries and per- centages of children with decayed teeth were significantly higher in children not taking 3 meals regularly, although the number of such children was small. Taking meals at regular times is also reported to be associated with the daily habits of individual children and seems to be effective in preventing dental caries6). The prevalence of dental caries and percent- ages of children with decayed teeth were sig- nificantly higher in Chinese children who, according to their parents/guardians, ate insufficient quantities of food, watched TV while eating meals, were picky about food, or were in the habit of talking too much during meals. Because the responses to these ques- tions relied on the subjective views of the individual parent/guardian, a reliable statisti- cal analysis may be difficult. However, watch- ing TV or talking too much while eating might extend mealtimes, thus increasing the
Table 7 Factors influencing risk of dental caries in Chinese children as identified by logistic regression analysis Factors strongly affecting presence/
absence of history of dental caries Factors strongly affecting presence/
absence of decayed teeth Odds ratio 95%CI p value Odds ratio 95%CI p value Snacks selected by children
themselves 4.00 1.32-13.70 0.0136 6.01 1.88-22.81 0.0019
Snack ingestion at time other
than between lunch and supper 3.11 1.07-9.61 0.0367 3.24 1.09-10.36 0.0341 Talking excessively while eating 3.71 1.25-12.06 0.0178 4.29 1.39-15.04 0.0108 Weaning at 25 months or later 3.68 1.24-12.04 0.0182 3.95 1.29-13.58 0.0151 p value of goodness-of-fit test; 0.6238 (dental caries), 0.6567 (decayed teeth)
Records of 74 children were used in logistic regression analysis.
Odds ratio indicates magnitude of increase in risk of dental caries associated with each factor listed above.
Factors more often seen in Chinese children than in Japanese children are shown in bold-faced type (Table 5).
snacking between meals3).
Chinese children received dental care less frequently than Japanese children. The per- centages of children who had visited dental clinics for prevention of dental caries or peri- odic dental checkups were especially low in China. Raising awareness of the need to visit dental clinics for prevention and early detec- tion of dental caries may be an issue requiring special effort. However, differences in the insurance system in how it affects rural and urban populations can make it particularly difficult for a rural migrant to the city to obtain dental care24,31). The present study revealed that while most of the Chinese chil- dren had visited dental clinics for treatment of dental caries, few had done so for preven- tive treatment, probably due to such difficul- ties. This then would explain why the preva- lence of dental caries and percentages of children with decayed teeth were high.
Therefore, the presence or absence of experi- ence of dental care was excluded from the logistic regression analysis.
The percentage of children living with grandparent(s) was higher in China than in Japan, but the percentage of children with siblings was lower in China due to the “one family, one child policy” in the country4). In Japan, living with grandparent(s) has been reported to increase risk of dental caries18,20), but no such tendency was revealed in the present study. According to our data, not only the grandparents of Chinese children, but also the parents were likely to have insuffi- cient knowledge about dental caries. Thus, living with grandparent(s) might not have been a factor in the present results as regards dental caries. Duration of sleep was signifi- cantly shorter in Chinese children as bedtime was approximately 0.4 hr (25 min) later there (data not shown). Although going to bed later can affect a child’s lifestyle, increasing the rate of post-supper snacking, for example, no effect was observed on risk for dental car- ies here.
Multiple logistic regression analysis
aged 3–5 years in Shanghai, China (Table 7).
These factors were in accordance with those identified in previous studies9,15,20,27). However,
“snacking at other times than the interval between lunch and supper” and “weaning at 24 months of age or later” are habits on which less attention has been paid in China than in Japan. Therefore, these factors require close attention.
The time of snack ingestion was between lunch and supper in most cases in Japan, whereas it varied greatly in China. In Japan, avoidance of snacking after supper is often advised, and this was reflected in the answers to the questionnaire9,15). Children selecting their own snack was also identified as a factor closely associated with the risk of dental car- ies. Snack ingestion in China appears to involve many factors possibly associated with the risk of dental caries, as is the case in Japan.
In terms of frequency of snack ingestion, the percentages of children with decayed teeth was significantly higher in Chinese children with the habit of snacking, even among those who snacked only once a day. This result may be explained by the fact that the percentages of children indicating that they did not ingest snacks was higher in China than in Japan.
However, as snacking may also serve to supple- ment the 3 daily meals1,14), advising avoiding snacking altogether cannot be recommended.
Moreover, the contents of foods and drinks commonly used as snacks, including the amount of sugar, varies greatly between China and Japan, indicating the need to investigate their effects in more detail26,29).
The number of children who had not yet achieved weaning by the age of 1 year 6 months was higher in China than in Japan.
Milk feeding at night was also more frequent and more prolonged in China. In this survey, no correlation was noted between milk feed- ing at night and the status of dental caries.
However, failure to achieve weaning by the age of 2 years can increase the risk of develop- ment of dental caries. Long-term and noctur- nal breastfeeding is considered to have the
receiving 100% breastfeeding is low in China, and even when nocturnal feeding is done, it is it unlikely to involve breast milk exclusively. In addition, the contents of artificial milk in China, such as sugar and fluoride, should be investigated. The response rate to questions pertaining to feeding was lower than that to the other questions, indicating the need to investigate this aspect in a larger number of subjects.
Identifying which factors are important in providing guidance on oral health may be useful in decreasing risk of dental caries among children living in urban areas of China. Moreover, such factors are likely to change with time. Therefore, our group will continue to monitor such trends in the future.
The results of this study indicate that pri- mary emphasis should be placed on limiting inter-meal snack ingestion and greater vigi- lance where children are still being breast- or bottle-fed at over 2 years in improving oral health in kindergarten children in Shanghai, China. However, parental selection of snacks and avoidance of too much talking during meals both had higher odds ratios than the other factors described above, urging careful attention here also. These findings will be utilized in providing oral health guidance to Chinese children in the future.
References
1) Ainuki T, Akamatsu R (2010) Associations among appetite, snacking, and body type dur- ing infant development. Nihon Koshu Eisei Zasshi 57: 95–103. (in Japanese)
2) Amano H, Nobuke H, Nagasaka N, Kamiyama K, One H, Sobue S, Nakata M, Ogura T, Deng H, Shi S, Liu D, Wei SH, Saito T, Ishikawa M, Takei T, Nonaka K, Ootani H, Shiono K, Shimizu H, Wang H, Zhang Y, Dong J, Hu D, Chan JC, Tong LS (1993) A study on the den- tal diseases and features of Chinese children—
daily feeding habits and environmental factors among Chinese children—. Shoni Shikagaku Zasshi 31: 606–640. (in Japanese)
(2014) Nutritional assessment for primary school children in tehran: an evaluation of dietary pattern with emphasis on snacks and meals consumption. Int J Prev Med 5:
611–616.
4) Basten S, Jiang Q (2014) China’s family plan- ning policies: recent reforms and future pros- pects. Stud Fam Plann 45: 493–509.
5) Batis C, Sotres-Alvarez D, Gordon-Larsen P, Mendez MA, Adair L, Popkin B (2014) Longitudinal analysis of dietary patterns in Chinese adults from 1991 to 2009. Br J Nutr 111: 1441–1451.
6) Bruno-Ambrosius K, Swanholm G, Twetman S (2005) Eating habits, smoking and tooth- brushing in relation to dental caries: a 3-year study in Swedish female teenagers. Int J Paediatr Dent 15: 190–196.
7) Cariño KM, Shinada K, Kawaguchi Y (2003) Early childhood caries in northern Philippines.
Community Dent Oral Epidemiol 31: 81–89.
8) Du M, Luo Y, Zeng X, Alkhatib N, Bedi R (2007) Caries in preschool children and its risk factors in 2 provinces in China.
Quintessence Int 38: 143–151.
9) Gao XL, McGrath C, Lin HC (2011) Oral health status of rural-urban migrant children in South China. Int J Paediatr Dent 21: 58–67.
10) Huntington NL, Kim IJ, Hughes CV (2002) Caries-risk factors for Hispanic children affected by early childhood caries. Pediatr Dent 24: 536–542.
11) Imai H, Kubo S, Yakushiji M, Liang Q, Shi S (2007) Present status of dental diseases in chil- dren in Shanghai Kindergarten—comparison between 1994 and 2004—. Shoni Shikagaku Zasshi 45: 51–57. (in Japanese)
12) Jiang X, Yang X, Zhang Y, Wang B, Sun L, Shang L (2014) Development and prelimi- nary validation of Chinese preschoolers’ eat- ing behavior questionnaire. PLoS One 9:
e88255.
13) Johansson I, Holgerson PL, Kressin NR, Nunn ME, Tanner AC (2010) Snacking habits and caries in young children. Caries Res 44:
421–430.
14) Kerr MA, McCrorie TA, Rennie KL, Wallace JM, Livingstone MB (2010) Snacking patterns according to location among Northern Ireland children. Int J Pediatr Obes 5:
243–249.
15) Li Y, Zhang Y, Yang R, Zhang Q, Zou J, Kang D (2011) Associations of social and behavioural factors with early childhood caries in Xiamen city in China. Int J Paediatr Dent 21: 103–111.
16) Lv J, Liu Q, Ren Y, Gong T, Wang S, Li L, col-
factors and their clustering in a representative urban population of adults: a cross-sectional study in Hangzhou, China. Int J Behav Nutr Phys Act 8: 40.
17) Ministry of Health, Labour and Welfare (2011) Survey of Dental Diseases. http: //www.mhlw.
go.jp/toukei/list/62-17.html (in Japanese) 18) Nishino M, Arita K, Aihara Y, Abe Y, Nasu K,
Abe N, Miki M (1991) Studies on a community dental health program for preschool children.
1. Analysis of multiple factors influencing on the prevalence of dental caries. Shoni Shikagaku Zasshi 29: 362–372. (in Japanese) 19) Ohshima M, Zhu L, Yamaguchi Y, Kikuchi M,
Nakajima I, Langham CS, Lin W, Otsuka K, Komiyama K (2009) Comparison of periodon- tal health status and oral health behavior between Japanese and Chinese dental stu- dents. J Oral Sci 51: 275–281.
20) Ohsuka K, Chino N, Nakagaki H, Kataoka I, Oshida Y, Ohsawa I, Sato Y (2009) Analysis of risk factors for dental caries in infants: a com- parison between urban and rural areas.
Environ Health Prev Med 14: 103–110.
21) Petersen PE, Kwan S, Zhu L, Zhang BX, Bian JY (2008) Effective use of fluorides in the People’s Republic of China—a model for WHO Mega Country initiatives. Community Dent Health 25: 257–267.
22) Prakash P, Subramaniam P, Durgesh BH, Konde S (2012) Prevalence of early childhood caries and associated risk factors in preschool children of urban Bangalore, India: A cross- sectional study. Eur J Dent 6: 141–152.
23) Qiu RM, Wong MC, Lo EC, Lin HC (2013) Relationship between children’s oral health- related behaviors and their caregiver’s sense of coherence. BMC Public Health 13: 239.
24) Waldman HB, Ackerman MB, Perlman SP (2014) Increasing use of dental services by children, but many are unable to secure needed care. J Clin Pediatr Dent 39: 9–11.
Asia Pac J Clin Nutr 17: 123–130.
26) Wang Z, Zhai F, Zhang B, Popkin BM (2012) Trends in Chinese snacking behaviors and pat- terns and the social-demographic role between 1991 and 2009. Asia Pac J Clin Nutr 21:
253–262.
27) Watanabe M, Wang DH, Ijichi A, Shirai C, Zou Y, Kubo M, Takemoto K, Masatomi C, Ogino K (2014) The influence of lifestyle on the inci- dence of dental caries among 3-year-old Japanese children. Int J Environ Res Public Health 11: 12611–12622.
28) World Health Organization (1997) Clinical assessment, Oral Health Surveys: Basic Methods, 4th ed., pp.31–53, World Health Organization, Geneva.
29) Zhai FY, Du SF, Wang ZH, Zhang JG, Du WW, Popkin BM (2014) Dynamics of the Chinese diet and the role of urbanicity, 1991–2011.
Obes Rev 15: 16–26.
30) Zhang S, Liu J, Lo EC, Chu CH (2014) Dental caries status of Bulang preschool children in Southwest China. BMC Oral Health 14: 16.
31) Zhang W, Wang X, Li J, Xu Z (2014) Uncompensated care for children without insurance or from low-income families in a Chinese children’s hospital. Med Sci Monit 20:
1162–1167.
32) Zhu L, Petersen PE, Wang HY, Bian JY, Zhang BX (2005) Oral health knowledge, attitudes and behaviour of adults in China. Int Dent J 55: 231–241.
Correspondence:
Dr. Atsuo Sakurai
Department of Pediatric Dentistry, Tokyo Dental College,
2-9-18 Misaki-cho, Chiyoda-ku, Tokyo 101-0061, Japan E-mail: [email protected]
